Field of Invention
The present invention relates to a voltage-sampling technology. More particularly, the present invention relates to a power conversion system and a voltage sampling device.
Description of Related Art
In a power system, a power conversion system has higher requirements of a current/voltage sensor as the grid voltage increases. Conventionally, an electromagnetic transformer is utilized to perform voltage sampling. However, the electromagnetic transformer has shortcomings such as possessing a complex insulation structure, being bulky and being expensive, etc. The electromagnetic transformer may also induce ferromagnetic resonance, which damages the equipments.
Developments of electronic transformers in recent years have improved a number of the shortcomings of an electromagnetic transformer, but certain theoretical and technical issues still remain in practical applications. It is very common for an electronic transformer to be interfered by common mode noise. When a sampled voltage possesses the common mode noise, an accuracy of the sampled voltage is dropped significantly. Consequently, a control circuit of the power conversion system cannot control an operation mode of the power conversion system accurately according to the sampled voltage, due to the interference caused by the common mode noise.
Therefore, an appropriate solution of a power conversion system and a voltage sampling device thereof has yet been developed, in order to address the above problems.